Voltage control circuit



Patented Dec. 28, 1948 UNITED STATES PATENT OFFICE/ff VOLTAGE CONTROL CIRCUIT SidneyyFrankel, Forest Hills, N. Y., lassignor to Federal Telephone and Radio Corporation, New York, N. Y., a corporation of Delaware Application October 9, 1944, Serial No. 557,805

(Cl. Z50-36) 7 Claims. l

This invention relates to voltage controls, and more particularly to circuits for providing direct current voltages in accordance with a primary controlling voltage.

VNumerous applications come to mind when given voltages are required to vbe provided in response to some primary or controlling voltage, One such application may be found in connection with the control of frequency in a reactance tube modulated oscillator.

In a circuit of this type, the tunable circuit ofthe oscillator ordinarily incorporates as part of' its circuit reactance a variable portion in the form of a so-called reactance tube. By applying a suitable controlling voltage to the grid or grids of the reactance tube the current in the plate circuit of the tube may be made to Vary its phase relationship with respect to that of the tunable ,circuit of the oscillator, giving the same effect as though a variable inductance r capacitance were connected in the oscillator circuit. The frequencyr of the oscillator is thus controllable by means of a signal on the grid of the reactance tube.

It is an object of this invention to provide a circuit for furnishing a voltage in response to a primary or controlling voltage of a given character. K

It is another object of this invention to provide a circuit wherein a variation in the amplitude of the output voltage may be obtained in response to and in accordance with the variable Width of input control voltage pulses.

Itis another object to provide means for converting a controlling Voltage wave into a biasingV Voltage for a reactance modulator.

It is a further object to provide lmeans for furnishing a biasing voltage to a reactance modulator, the value of which is a function of the variation with respect to time within a given periodnf the controlling Voltage.

In accordance with my invention, I provide a trigger circuit for generating pulses which is energized from circuits adapted to control or determine the width of the pulses generated in accordance with a given variable, such as signal frequency. The pulses thus obtained are used to control a so-called bias generator which includes a capacitance, the charging and discharging of which is timed by the pulses and the resulting voltage of which is applied to the grid of a reactance tube. This, added to the voltage from a fixed bias potential source results in an overall bias for the tube and is effective in determining the .f plate .current of the reactance modulator,

2 whereby the frequency of the oscillator maybe varied as noted hereinabove, yThe oscillator is arranged to be keyed oif vduring the period when the change in the biasing voltage forthe modu-v lator takes place, and becomes operative again when the biasing voltage has assumed its yfinal value. i

These and other features and objects will become apparent, as reference is had to the following detailed description to be read in connection with the accompanying drawings, in which:`

Fig. l is an illustration partly in block and partly in schematic form of a circuit in accord.- ance with my invention; and f .1.

Fig. 2 is a graphical illustration showing the steps of operation. j

Referring to Fig. 1, the controlling or primary Voltage pulses in accordance with graph a, Fig. 2 may be obtained from a trigger type circuit pulse generator I, which is being energized and cone. trolled from a pulse width determining circuiti; The pulse width determining circuit may` beany one of a number of suitable devices which, by their voltage output, control the Width of the pulses generated by the trigger circuit l. An example of such a circuit has been described in the vcopendl ing application of E. Labin, and S. Frankel, Serial No. 556,742, filed October 2, 1944, wherein a series of starting and stopping pulses are obtained for, the actuation of a trigger circuit, separated by a time interval which is a measure of the radio frequency to which a receiving circuit is tuned at a given moment during a panoramic type fre-y quency scanning cycle. The trigger circuit 4to which these actuating starting and stopping pulses are applied,` may be of the type known'as the Eccles-Jordan trigger circuitkwhich, initselfr is known in the art and need not be described.- here in detail. It may suffice at this time to state that this .type of circuit may be actuatedl by a sharply defined starting pulse ofk agivenpolarity to provide a constant voltage which is terminated abruptly as a so-called stopping pulse also sharply defined but of opposite polarity, is applied to the circuit, the output of the trigger circuit being inthe form of square topped pulses as in graph a. These pulses are applied to a bias; voltage generating circuit indicated at 3. As the; leading edge of these pulses (graph a) is applied to a diode 4 over a resistor 5, the diode is rendered conductive as the applied pulse voltage is posi:`

tive and the cathode of the diode is at zero or ground potential. The pulses are thus able to' charge a capacitor 6 for the period of their dura-'J1 tion. Sinc'ethe capacitor 6 is connected to groud "i tim at 1, and since for the duration of the pulses (graph a), the diode 4 may be considered a perfect conductor between the resistor 5 and the con- 8, the plate of which is connected to the junc-A tion of the cathode of the diode 4-,with-the condenser 6, and the cathode of which is also connected to ground at l. The conductivity of this triode is controlled by means Vof `afg-grid i9 "which is lxedly biased to a negative potential 'from 4a source I0. A circuit also has ribeenprovided for differentiating the pulses of graph a., consisting of a condenser II and airesistor I2 in series connecting the output terminal of the trigger circuit ,'I lztoggroundil. :The differentiatingsvoltage pulses 'duetoirtheleading andi-trailing edges-'of the :pulses of graph a, respectively, which Vmay vbe obtained `across the resistorf If2A are shownrinv graphfbfwherein the :leading edge `oi" ithe lsquare :pulses result inssharply` dened :positive: and bthe :trailing edges in sharp negative pulses.

ilhelgrid :i9 of the triode f8 is connected to the junction 'point yI^3 between Ethe f-condenser 'I I Iand the resistor i I2, .whereby 'the differenti-ating pulses serve I to :reduce fto a :greater 'or lesserfextent f the negative gbias maintainedbn the-rg-rid 9 due to yth'efsource I0. Thefbias lforithe' triode'f is chosen in such a Way as toirenderftheitubevcon'ductive when :the `positive differentiating :pulses -are applied, while the negative pulsesonly-servatoincrease fthe negative lvbias and therefore ydo not aiect thefconductivity of Iitheftriode. Assoon-as the conductivityofthe triode has beeninterruptedf-that is, Vrestored toits normal state,-the condenser '6 will --be `charging 'up -due :to =the `pulses df VLgraph 'a being applied thereto throttgh the now conductivediodesli. vThe Jcondenser Iwill charge tup substantiallyexponentially in accordance withfltheportion If'4 of-graph'c. \'.Ilnev voltage of thesconden'ser will'conti-nue tofincrea-se inithis exponentialmannerforithe-durationofthapulses I5 fg'raphsa). As soon vas any ofithe-fpulses "Hi vare terminated, the voltage on =theIcondenser ase sumes 'the' constant value indicated at 1If6-vin graph c land :continues lsubstantially at this value until thecondenserfis again-able to ydischarge tofground upon rconductivity l*being -festablis'hed through triodel when a positiveJ differentiating 'vltag'e'pulse (graphit) -is v'applied'to the grdl whenfthe=next pulsed-f5 Loccurs. Itis =thus apparent that 'the voltage obtainable 'from Ythe condenser over -a connection lv'I fisdirectly controlled by thew'idth Of thepulses I5 applied through the'diode. The variation of the voltage'onfthe condenser-L6 with the 'width of Ythe pulse I5 has-been indicated by the broken'lines connecting two diierentwidths of the tpulses I I 5 iWith their respective'voltagelevels .Sin graph fc.y The condenser 4volta-ge -whichis shown to be .of positive polarity in graph'c `is appliedtof a -reactance modulator circuit VI 8 which normally is xedly Abiased to a negative 4vpotential from fa bias potential source I9. "This --negative bias ."for -the reactance lmodulator is indicated by the :broken line 1120 :at lthe :value "Ecl in :graph 'c Asffthe :voltage 'obtained jfrom fthe condenser over the @connection :I'I Lis ,fadded Vto z.the abias Ecl from the-source ./I'9, the voltage ivalues y.at anyioneztime are added algebraically,. resulting :in ea :final fbias having the malue .,Ecz for 'fthe freactance zmodulator. Since the modulator I8 is connected to control the tuning circuit and thereby the frequency of an oscillator 2l, the oscillator, for the period during which the bias voltage from the condenser 6 may be changing, that is at least for the duration of the pulses I5, may be keyed oli" by pulses of the type shown at 22 in graph d,

',whicheimay be supplied'bya keyerecircut 23.

It-may be nseen that, iin 'accordance with the above description, any primary control condition v`Which may be made to result in pulses I5 indieating by diierent Widths a variable controlling factor, may be made to produce a voltage of an ramplitude -valuefcorresponding to the width of these controlling pulses.

Although I have shown and described a spezcicfapparatus fior-carrying out the method of my invention, it will be understood that the apparatus may be modified Without departing from the scope of the invention. Particularly, it is pointed outY that-'while'the inventionihasi beendescribed =in connection with =a frequency fcontrl circuit :as indicated fby the reaotanceanodiilator and oscillator Z, other applications fmayfreadily occur to one vskilled vin 'i the art for the Woltage .generating .circuit 3 'controlled by theftriggencircuit I. Itiwillbe understoodltherefore,fthatithe formlherein :shown and described'lis 'tol-befregarded iillustrative ofthe invention only fand `-not as limiting the objects thereof.

l. A radio system Lfor 'controlling Tthe frequency lof :an `oscillator in =response -=to and in accordance with fcontrolling pulses lof varying widths, ycomprising a l'tirigger 4circuit dor Agenerating l.pulses of varying widths, a 4source o'f prim-ary potential *for fcontrolling the width ro'i said=pulsesoperatively associated withsaid-trigger circuit, means ifor vestablishing fa voltage-in accordance' with the time of application i thereto of la `given Vprimary Avoltage 4'connected to -receive said -controlling pulses, Lmeans `connecting Asaid means `'for establishing to said trigger circuit operatively controlled by said pulses, means for returning :said fmeans for establishing to zero voltage Iwith the 4"beginning `of Aeach "pulse, "an oscillator, and sa reactance-modulator for 'controlling the frequency of said oscillator 4'connected to receive tli-evoltagefo'f said -means A"for establishing. '2. Ara-dio systemlion-'controlling'therfrequency of r:an oscillator Lin vrespon-se -to 'and in accordance with controlling pulses fo Varying'widthsycomprising'a :trigger "circuit v1for generating -pulses foi varying widths,I afsource Aof primary'A potential for controlling the 'width of said-'pulses operatively associ-ated with -said `trigger circuit, means 'for establishing a `voltage Lin accordance lwith #the time of application -of -a given vprimary voltage connected `to f-receive said 'controlling' Jpulses, means connecting saidmeansforestablishingto said trigger 4circuit operatively controlled `"by said pulses, Ymeans for v'returning said 'means @for establishing 4to Izero vvoltage `with 4the Ilbeginning oi each Apulse, `an oscillator, a reactan modulater for controlling *theifrequency of said voscillator `connected "to lreceive "the lvoltage "of "said means for f establishing, and :means "f or supplying keying :voltages to said 'oscillator ,for `keying the same Joli` for at least -the Vduration of nsaid controlling pulses.y

3. fAn :electrical system for providing a fiina'l voltage .proportional to the =varying widths vof control pulses comprising means fior `simultaneously'integratingiand diierentiatingssaid ccnntrol pulses to obtain separate outputs thereof, means for applying said differentiated output to reduce said integrated output to a given amplitude at the beginning of the application of said pulse to said integrating means, a load circuit, and means for applying said integrated output to said load circuit.

4. An electrical system for providing a iinal voltage having an amplitude proportional to the varying widths of control pulses comprising a storage means, means for applying a portion of said control pulses to said storage means, means for differentiating a portion of said control pulses to obtain a differentiated output thereof, discharge means for said storage means, and means for energizing said discharge means with said differentiated output, whereby the energy in said storage means is reduced to a given level, a load circuit and means for applying the energy of said storage means to said load circuit.

5. An arrangement according to claim 4, wherein said discharge means comprises a gasiilled electron discharge device.

6. An arrangement according to claim 5, wherein said means for differentiating comprises a resistance-capacitance network.

'7. An electrical system for providing a iinal voltage having an amplitude proportional to the varying widths of control pulses comprising a storage means, a rectifier circuit, means for charging said storage means with said control pulses through said rectier circuit, a gas-filled electron discharge device coupled across said storage means, said device comprising a control electrode, means for differentiating said control pulses, to obtain an output thereof, means for applying said differentiated output to said control electrode whereby said device discharges said storage means to a given level.

SIDNEY FRANKEL.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 2,008,730 Smede July 23, 1935 2,203,750 Sherman June 11, 1940 2,231,591 Pieplow Feb. 11, 1941 

